Pahimar just tweeted about this very very new mod (no really, the MCF thread was created less than three hours ago).
Blood Magic
It makes use of the new health regeneration mechanic in Minecraft 1.6, where healing up is no longer free (it rapidly drains your food bar). I think this is a good candidate for the Magic World pack (or even Jaded's Magic Farm pack, where food plays an even bigger role)
also made by wayoftime an active member of the forums